Humans today suffer from many of the same health problems that they always have, the only difference is that we now have a somewhat better understanding of the causes. In ancient times, one of the more common forms of illness (at least by the similar-appearing symptoms) was attributed to being "moon struck" - the New Testament Greek term for it is pronounced sel-ay-nee-ad-zom-ahee, and is translated as "lunatic" in some versions of The Bible (the English word "lunatic" is based on the Latin word luna, meaning moon). It was a term that included a wide variety of inflictions, none of which actually had anything to do with the moon, ranging from people with mental illness, to those who were affected by occasional epileptic seizures, to others who were actually demon possessed. During His ministry, Jesus Christ never made a distinction between them; instead, by means of the Holy Spirit, He simply healed them all.
Right from the start of His public teaching, not long after He called the twelve apostles, the Messiah healed numerous people of many forms of illness, and possession, including many so-called "lunatics":
"From that time Jesus began to preach, and to say, Repent: for the Kingdom of heaven is at hand. And Jesus, walking by The Sea Of Galilee, saw two brethren, Simon called Peter, and Andrew his brother, casting a net into the sea: for they were fishers. And He saith unto them, Follow Me, and I will make you Fishers Of Men. And they straightway left their nets, and followed Him. And going on from thence, He saw other two brethren, James the son of Zebedee, and John his brother, in a ship with Zebedee their father, mending their nets; and He called them. And they immediately left the ship and their father, and followed Him."
"And Jesus went about all Galilee, teaching in their Synagogues, and preaching the Gospel of the Kingdom, and healing all manner of sickness and all manner of disease among the people. And His fame went throughout all Syria: and they brought unto Him all sick people that were taken with divers diseases and torments, and those which were possessed with devils, and those which were lunatic, and those that had the palsy; and He healed them." (Matthew 4:17-24 KJV)
In the case of a young "lunatic" who was suffering from seizures, Jesus explained how faith is vital before, God willing, according to God's Plan and Purpose, the Holy Spirit (see The Spirit Of God) heals:
"And when they were come to the multitude, there came to Him a certain man, kneeling down to Him, and saying, Lord, have mercy on my son: for he is a lunatic, and sore vexed: for ofttimes he falleth into the fire, and oft into the water. And I brought him to Thy disciples, and they could not cure him."
"Then Jesus answered and said, O faithless and perverse generation, how long shall I be with you? How long shall I suffer you? bring him hither to Me."
"And Jesus rebuked the devil; and he departed out of him: and the child was cured from that very hour."
"Then came the disciples to Jesus apart, and said, Why could not we cast him out? And Jesus said unto them, Because of your unbelief: for verily I say unto you, If ye have faith as a grain of mustard seed, ye shall say unto this mountain, Remove hence to yonder place; and it shall remove; and nothing shall be impossible unto you." (Matthew 17:14-20 KJV)
Fact Finder: How are demons able to "possess" people? How can demon possession be cured?
See Casting Out Demons